ABSTRACT

A new digital oil and gas well spot map is being prepared for Morrow County, Ohio. This map will show the location of all wells drilled to the Trenton Limestone or deeper. Data for this map was collected under a contract with the U.S. Department of Energy to add data to the Tertiary Oil Recovery Information System (TORTS) to estimate 80 per cent of original oil in place in the Ohio portion of the Appalachian Basin. Well locations were digitized from township well-spot maps. Approximately 3,150 wells have been drilled to the Trenton Limestone or deeper in Morrow County, Ohio, almost entirely the result of the drilling boom of the 1960's. Approximately 1,000 oil wells and combination wells have been reported productive from the Knox Dolomite. 532 wells have a reported total production of 29,000,000 barrels of oil (bo). Using production histories and gross decline curves, the estimated total cumulative production has been 37,700,000 bo with approximately 6,500,000 bo recoverable reserves remaining.

Simple production statistics have been computed with available data for all the townships in Morrow County. The Cambrian Knox Dolomite (Trempealeau of drillers) is the dominant producing reservoir. Hydrocarbons are entrapped near the Knox unconformity primarily in paleotopographic hills where dolomitization has resulted in porosity development as solution-enlarged fractures and vugs. The average producing reservoir data for the entire field is as follows: Temperature = 87º; depth = 3500 feet; IP after treatment, oil = 185 bo, gas = 50 MCF; log porosity =10.3%; initial GOR = 300; net pay = 23 feet; RW = 0.06; SW = 22%; and productive area = 14,000 acres. Available well data was gathered and placed into a spreadsheet and sorted by estimated cumulative oil production per township. Histograms were made by each data type in an attempt to correlate average reservoir data with greatest estimated cumulative oil production by township. The data collected reveals that the most significant producing townships in Morrow County are Canaan, Peru, Lincoln, Gilead, and Cardington. The only reservoir data correlating to the greater producing townships is average initial oil potential after treatment. The lack of correlation of other data for the greater producing townships may he due to the general unavailbility of data. Low numbers of data points may not adequately represent reservoir data for the township. An expanded reservoir study is required to further analyze the Knox Dolomite reservoir for producing townships of the Morrow Consolidated field.

FIGURE 1:

Ohio Geological Survey Open-file Map 304, showing wells reaching the Trenton Limestone and deeper in Morrow County.

TABLE 1:

Example of data elements summarized in the TORIS database for the Morrow Consolidated field.